Re: [R] transparent surface in rgl

From: Duncan Murdoch <murdoch_at_stats.uwo.ca>
Date: Thu 06 Oct 2005 - 01:33:47 EST

On 10/5/2005 11:10 AM, Prof Brian Ripley wrote:
> On Wed, 5 Oct 2005, Duncan Murdoch wrote:
>

>> On 10/5/2005 9:31 AM, Prof. Paul R. Fisher wrote:
>>> Hi all
>>> I am a complete newbie to this list (just subscribed) and a newcomer to
>>> R (an S user from olden times). I have been using scatter3d to create a
>>> 3d scatter plot with surface. The graphic is created within the rgl
>>> package and I have used rgl.postscript to export it so I can generate a
>>> publication quality image. My problem is that the plotted surface is no
>>> longer transparent in the postscript output ie. the rgl.spheres that are
>>> behind the surface disappear in the postscript image. Can't seem to find
>>> any info on this anywhere. Am I doing something wrong? Is there an easy fix?
>>
>> I think Postscript doesn't support transparency (or at least the version
>> of Postscript that the rgl.postcript function targets doesn't support
>> it).  You may have to export a bitmapped format using the rgl.snapshot()
>> function.  If your original window is very large this may give you good
>> enough quality.

>
> Common PostScript (level 2) does not support either full or partial
> transparency (and I guess partial transparency is meant here or the
> surface could just not be plotted). It would be good to have a rgl.pdf
> which did. These days PDF is the `portable PostScript' and since version
> 1.4 has had alpha-channel supoort.
>
> Ref:
>
> http://en.wikipedia.org/wiki/Transparent_pixels#Transparency_in_PostScript
>
>

The library we use (GL2PS) apparently supports PDF output, and that's one of the format options for rgl.postscript(), so maybe we already do support that. I haven't tried it.

Duncan Murdoch



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